Celebrities undertake a series of extreme tasks, including jumping backwards out of a helicopter and hand to hand combat, as they begin the challenge of completing the gruelling SAS selection course.

Recruits are pushed to tackle their fears head on in a 60m high forward abseil, while a brutal game of murderball on a black mud plain leaves one recruit with a near concussion.

In an abandoned abattoir, recruits face a life or death decision before they are drilled physically into the early hours of the morning. Will they bow out from exhaustion or find the true grit needed?

In freezing waters with plummeting body temperatures, recruits wait to be rescued by their teammates before they face a test of pure grunt and teamwork. An emotional departure surprises the group.

In a punishing day, recruits crawl across a jagged ravine on a single rope above the ocean; are submerged in crashing, cold surf; and face a physical drilling that leaves them on the brink of collapse.

The fatigued recruits drop from a helicopter into 4-degree water carrying 20kg backpacks, before making their way to shore as a group then racing to the top of a mountain.

Armed with rifles, recruits are tasked with a hostage rescue mission, before taking on their most dangerous task yet in near freezing water.

Recruits are brutally awoken by the sound of gunfire and a botched rescue attempt unfolds. Messages from home test the recruits' emotional resolve while a relentless pack march takes its toll.

In a dangerous backward fall, the life of the jumper is in the hands of a fellow recruit. During an honesty test, some gobsmacking truths are shared. And a simple mistake results in a serious injury.

Recruits race up a snow-covered mountain dragging a 60kg sled. Exhausted, they must then swim under ice, battling hypothermic conditions, only to discover the weakest will be sent home.

In a daunting challenge, recruits are tasked with rescuing a downed pilot. As bombs explode and guns fire, they must make the right decision amidst the mayhem. After a brutal combat course, an explosion on base has an unexpected outcome.

Recruits are chased overland in near freezing temperatures. Once captured, they face intense interrogation before they attempt the final phase of the course, a series of brutal physical tasks called The Sickener, designed to push them over the edge. Who will prove worthy of passing SAS selection?

Eighteen celebrity recruits undertake physical and psychological tasks to strip them of their egos. On arrival, the recruits face tear gas exposure and interrogation by the ex-special forces' instructors.

The celebrity recruits must use courage while facing a terrifying balancing act, 30m above ground. Back at base, they face claustrophobia by negotiating a narrow underground tunnel.

The celebrity recruits are submerged in a vehicle underwater, forcing them to control their panic while holding their breath. They also undertake a covert drill, to test their integrity.

Fourteen everyday Aussies begin the first day of a brutal one week version of the SAS selection course. Only the toughest will survive Hell Week.

The recruits must fight icy waters and make a brutal climb, then attempt a gruelling task over rocky terrain. But with growing fatigue, recruits turn against each other in a bid to survive.

Seventeen celebrity recruits have the guts to sign up for the most brutal Special Forces selection course. Their first initiation is to be set on fire, and then survive a plane crash simulation.

Celebrity recruits must remain calm in a terrifying balancing act high above a factory floor. Later, they face a dangerous Navy SEAL drowning survival test called 'the beehive'.

Entering a dark tunnel filled with obstacles and water, recruits must remain adaptable and battle claustrophobia. Tensions boil over as the recruits attempt to work together.

Recruits face a high adrenalin task as they leap from a moving zodiac into a moving helicopter. Pepper spray conditioning pushes some over the edge. Only with the right mindset will they succeed.

Friction among the recruits explodes as leadership is put to the test in a brutal Navy SEAL surf battle and a grueling team waterfall climb.

Recruits take part in an extreme tug of war. Facing off against each other, the loser will be dragged off a 100 metre cliff. An assault course will leave them bruised and battered.

In a heart-stopping abduction scenario, recruits must escape from the trunk of a moving car, bringing out reckless behaviour in some.

14 celebrity recruits are dropped into the harsh and unforgiving Jordanian desert, surrendering themselves to the brutal SAS selection course.

The 13 remaining celebrities face a day of extreme training that claims two voluntary withdrawals and one medical withdrawal.

The 10 remaining recruits are tested with tasks requiring pinpoint accuracy and precision, in two life or death scenarios.

A night beasting claims another withdrawal. The recruits come under attack and capture before being facing each other in hand-to-hand combat.

The nine remaining recruits learn the hard way about drone warfare. A mountain rappel almost ends in disaster.

An aggressive game of murderball pushes the recruits to their limits before a shock VW and a backbreaking grunt task resulting in an unlikely hero.

A rare morning of good morale is destroyed by a worrying accident before a high-pressure tactical driving task.

Three days to go and six recruits left to show courage in an excruciating rope hang and water to Blackhawk exfiltration before emotional letters from home and a night beasting that claims another number.

Just five recruits remain as they're sniper skills put to the test.

The final four must combine all the skills they've learnt to a three-phase final mission, to pass the course, and make selection.